Sign Sign, Everywhere a Sign

Woman walks into a bookstore. Goes up to the clerk and tells them that she's an author and would like to sign copies of her book. Bookstore clerk agrees to this and within half an hour both store and author are happy. Little "Autographed by the Author" stickers are slapped on the title, thereby increasing the likelihood that someone might want to buy the volume.

The only problem? That wasn't the author. Just some schmuck off the street, and the clerk never bothered to do a check or anything.

To the best of my knowledge, the above situation has never occurred. Lisa Graff, who recently took her own autonomous signing to a B&N, speculates on the implications of letting any old person sign some books willy-nilly. I find myself intrigued. Let's say I walk into the Union Square Barnes & Nobles and say that I'm Kirsten Miller and I want to sign all their copies of Kiki Strike. What are the odds that they'd call me on that one?

And for that matter, I wonder what the stats are on signed books vs. unsigned books in terms of sales? We all think the autographed do better. What if that's not the case?